| dc.description.abstract | Laser cladding is gaining acceptance for restoration of turbine and compressor shafts, which has resulted in increased customer demand for laser cladding options. This has increased the number of laser welding suppliers, who are offering a variety of solutions. Therefore, it is important to understand the basic capabilities, limitations, and potential pitfalls of the laser cladding process. For example, it is still unclear how the process should be qualified to ensure that laser weld repairs meet the requirements for the given application. As with any welding process, the desired outcome is a metallurgically sound deposit that meets or exceeds the minimum design criteria for the application. Filler material alloy selection, form, and delivery methods can have a significant impact on the quality and suitability of the weld deposit. For example, all fusion welding processes generate a heat affected zone, and the properties in that region are unlikely to meet base metal requirements without a post weld heat treatment when the base metal is quenched and tempered steel, which is commonly used for turbomachinery shafts. However, it is commonly claimed that a post weld heat treatment is not required with laser welding due to the low heat input of the process, which greatly reduces the size of the heat affected zone. While this may be true in some cases, it is important to recognize that the heat affected zone will still be present and testing must be completed to ensure that the repaired component will be suitable for the application. This paper discusses the most commonly repaired shaft areas, the risks associated with laser welding in these locations, and the types of tests that should be required to qualify a procedure. Additionally, examples of successful repairs are shared including experimental results from the qualification process. | |
